I have looked at Condition 13(e) of NR's current Conditions of Carriage. This states that it is applicable only where we intend to use a route not covered by (a) and (b) of those conditions.
Condition 13(e) states "
If you make your journey by a route other than those referred to in (a) and (b) above, you will be liable to pay an excess fare. This excess fare will be the difference between the price paid for the ticket you hold and the price of the lowest priced ticket(s) available at a ticket office for immediate travel that would have entitled you to travel by that route", but it does not include the word "
only". There are other circumstances in which an excess fare may be payable.
In this instance, both Bristol Temple M - Yeovil - Weymouth and Bristol - Salisbury - Eastleigh - Southampton Group - Weymouth are permitted routes, as shown in post #7.
Fares between Bristol Temple M and Weymouth are sold with one of three routings:
- route Not Via London. This is mostly used via Reading.
- route Via Salisbury, and
- route Via Yeovil.
The right to pay an excess fare if travelling outward via Yeovil and returning via Salisbury derives from page 6 of the instructions "
How to use the National Routeing Guide":
CALCULATING EXCESS FARES
On occasions the Routing Guide will prevent a customer from making their preferred journey. In such circumstances and where appropriate, the customer should be offered the opportunity to purchase an excess fare ticket, prior to travel, which allows the journey to be made by their preferred route.
Where a journey is undertaken by an alternative route to that for which the ticket was originally purchased, and for which a higher fare applies, additional payment is required to enable the customer to make or complete their revised travel arrangements.
This option may not apply to customers holding Advance tickets, or tickets which are available by specified trains or endorsed for travel only by the services of a particular train operator.
DUAL ROUTE AVAILABILITY
Where two or more permitted routes are available for a specific journey, customers may wish to travel out by one route and return by another. If a higher fare applies for the return leg of the journey the customer should be issued with a ticket for the more direct route and an excess fare issued to cover the difference in fare for the return routeing. This option should be made available to customers who wish to pre-book a dual routed ticket prior to travel.
The alternative journey MUST relate to the same routeing points for the origin and destination stations.
This option may not apply to customers holding Advance tickets, or tickets which are available by specified trains or endorsed for travel only by the services of a particular train operator.
I interpret from Step 7 of the NRG that BW + CW is the permitted route and not CW + BW.
This interpretation is incorrect. Page F8 of
The National Routeing Guide in Detail explains that permitted routes are the same in both directions of travel, therefore route code BW+CW is identical to route code CW+BW.
Section C (the yellow pages) lists all journeys between pairs of routeing points and the route codes for the permitted routes. Journeys are listed alphabetically by origin and destination. As the permitted routes are the same in both directions of travel it makes no difference which way round the journey is looked up. Sheffield to Inverness has exactly the same permitted routes as Inverness to Sheffield and the same is true of every other listed journey.
all my attempts to use the Journey Planner to find a fare from W to B via SA are declined, presumably because it would involve travellers to B to double back (which is not allowed without a specific easement).
This is due to an inadequacy in the journey planners, not to you. None of the journey planners have been designed to cope with a return journey where the outward leg has a different route from the return leg.
In this instance, search for Bristol Temple M to Weymouth via Yeovil to find a suitable itinerary for your outward leg. Then search for Weymouth to Bristol Temple M via Southampton Airport Parkway to find a suitable itinerary for your return leg (i.e. your onward leg to Southampton Airport Parkway). Unfortunately, internet ticket selling sites are unable to sell excess fares, so you'll have to buy these at a station or on a train.
But neither leg involves a double back. Doubling back is passing through the same station more than once on the same leg of a journey. Neither the outward nor the return legs of the journey quoted in post #7 do this. In practice, you would travel only between the stations I have shown in bold in post #7.
I am aware from the forum that in the past there appears to have been a methodology of the excess fare being calculated on half the difference between the £59.50 and price of the cheapest return (£134.75) but I have found nothing yet that supports the excess fare being calculated on a basis different from that under 13(e).
Some years ago, both a change of route excess and a change of ticket type excess were charged at half the difference if the change applied to only one leg of a return journey.
This led to anomalies with respect to changes of ticket type, and that type of excess was changed to the full difference in price. The anomalies did not occur with change of route excesses, and the calculation of this type of excess fare did not change.
On 10 May 2016, I successfully purchased an Off-Peak Day Return Bournemouth - Epsom
route via Barnham together with an excess fare ticket for the outward leg only to
route Not Via London. I paid the route via Barnham price plus half the difference to the route Not Via London price.
If the half the difference option is indeed still available, it would be very helpful if you could also tell me where I can find this in print.
The instructions currently appear in internal railway industry documentation only, but I think the relevant document was placed on the internet a few years ago. If I can find it using a web archive site, I'll amend this reply to include the link.
There is more detail on excess fares on
this page of our
Rail Fares & Ticketing Guide.